On Halloween, Monk visits his brother Ambrose in his childhood home to await a visit from his long-absent father, but things take a strange turn when a masked trick-or-treater repeatedly tries to steal Halloween candy from Ambrose's house.

Monk goes undercover as an office worker and revels in the office routines and actually starts making friends and a possible romance as he tries to solve a murder that occurred in a parking garage next to the office building as well as who injured the hand of the man who hired him whose hand was slammed into a car door probably by the murderer. But Monk's new found popularity may come to a screeching halt if he won't put on the pair of used bowling shoes for the showdown match between his office team and their rival team.